Rest in peace, Steller's sea cow.

What would you do if you had a time machine? Meet your distant ancestors? Kill baby Hitler? See some of magnificent animals that are now extinct?

Unknown Tourism, a series of vintage-style images by travel company Expedia UK, is a throwback tribute to some of the creatures we’ll never get to see. Human activity has wiped most of them off the face of the planet. (The golden toad is the one possible exception ― some scientists believe that creature died off as a result of manmade climate change, but one study suggests this may not have been the case.)

“These posters were intended as a way of commemorating some of the incredible wildlife we’ve lost, as well as revealing something about these countries that travellers wouldn’t necessarily think of when they visit,” Matt Lindley, who worked with Expedia on the project, told The Huffington Post in an email. “That said, if their visual appeal can also get more people thinking about biodiversity loss, that can only be a good thing.”

For now, he added, the images are only available online.

In an era where numerous animals ― including the mountain gorilla, the black rhino and the pangolin ― face grave danger from humans, the posters are an eerie reminder of what we stand to lose.

Alaska: Go Glacial with the Steller's Sea Cow

Expedia UK

Closely related to the manatee, this gentle giant meandered the waters of the Bering Sea in relative peace until 1741, when sailors from a marooned expedition began hunting it for sustenance.

Sea cows became a popular target for hunters after word got out that they made for good eating, and were wiped out by 1768.

Mauritius: Meet The Dodo, Our Friendliest Resident

Expedia UK

The dodo, last spotted in 1662, is an iconic symbol of human-driven extinction. Although the flightless bird is typically portrayed as having been too stupid to avoid hunters, more recent research suggests that's inaccurate. Instead, humans may have contributed to the creature's extinction by introducing invasive species like pigs that ate dodo eggs and devoured the bird's food sources.

New Zealand : Walk with the Moa in the Land of Giants

Expedia UK

Humans are to blame for the extinction of the moa, a large flightless bird that once roamed New Zealand, according to a 2014 genetic study. People hunted both adult and young moas, driving the bird to extinction sometime in the late 13th century.

Tasmania: Earn Your Stripes, See The Thylacine

Expedia UK

Some zoologists contend that this dog-like marsupial still exists in Tasmania, but the International Union for Conservation of Nature and Natural Resources categorizes the thylacine as extinct. People began killing off the animal in the 1800s to protect their sheep, and the last known thylacine died in captivity in 1936.

Jamaica: The Gem of the Tropics, Home of the Giant Galliwasp

Expedia UK

The last recorded sighting of this lizard was in 1840. Researchers believe the extinction followed the introduction of predatory species like mongooses, which wiped out the reptiles, the IUCN notes.

Costa Rica: Discover The Golden Toad, A National Treasure

Expedia UK

Scientists long believed that the golden toad, last seen in 1989, went extinct due to the effects of human-driven climate change. Hotter, drier weather in Costa Rica created the perfect environment for a deadly disease that wiped out the amphibian's population. However, a 2010 study suggested that this particular local temperature shift was caused by natural weather events. That said, not all scientists were convinced by the new study, and even the lead researcher emphasized that the results "shouldn’t be any comfort" when it comes to considering the long-term dangers of manmade climate change.

Clarification: Language has been amended to better summarize the findings of the 2010 study on the extinction of the Costa Rican golden toads.